Known painting devices can include atomizers for painting workpieces. During the painting process, these atomize a liquid coating material into a multiplicity of very small droplets, for example, in a range of from 5 μm to 50 μm droplet diameter, which are then directed towards the workpiece to be painted, such as by an air stream emanating from the atomizer. The mixing of the paint droplets or paint particles with the air gives rise to a paint mist during the operation of the painting device. Examples of atomizers of this kind are air atomizers or rotary atomizers.
An industrial painting process can take place in a paint booth, in which suitable climatic conditions can be maintained. For example, paint booths have devices for cleaning the air in order to free the ambient air in the booth from the portion of the paint particles atomized which do not reach the workpiece during the painting process owing to the level of efficiency, for example, and to make available the air cleaned in this way again at a desired temperature, for example, 24° C.
However, paint mist can also be introduced into the ambient air in the booth during a change of color or during an “initial pressurized infeed” operation, for example. It is desirable for cleaning purposes, when changing the color, to force residues of the original coating material forwards out of the paint supply system through the atomizer, subsequently to do the same with a cleaning agent and then to feed the new coating material in under pressure. This takes place in the paint booth. During this process, the coating material and/or solvent is only partially atomized and carried into the ambient air in the paint booth. Owing to switching operations or indeed startup or braking operations, for example, in the case of a rotary atomizer, there are therefore relatively large droplets of paint or solvent in the paint mist produced in this way.
To remove paint or solvent mist from the ambient air in the booth, use is made of devices called separators, which ultimately filter out the paint particles as waste, which then can be disposed. “Wet” and “dry” separators can be used. In the case of wet separators, the paint particles are initially introduced into a wash-out-system water circuit that can be provided, after which the paint particles are removed from the water. The waste which arises is then separated from the water and disposed of as paint sludge.
In some respects, dry separators can be advantageous compared with wet separators, particularly because there is no need to provide a water circuit. Moreover, drying of the air made humid by the water circuit in the case of wet separators can be eliminated, and therefore dry separators can also prove advantageous in terms of energy considerations.
However, the filtering effect of dry separators can be less effective, especially in the case of droplets of coating material of relatively large diameter, and therefore increased contamination of the painting installation and/or of the air-conditioning system can occur during prolonged operation. This is because dry separation can involve the use of a powdered binder, with the result that separation can be inadequate in the case of large particles or droplets owing to the relatively small area of contact between the binder and the paint particles in that case. The paint mist which is introduced into the ambient air in the booth during a change of color, containing as it does some paint particles or droplets which are of significantly larger size, therefore can present issues for dry separation.
Exemplary embodiments can provide a device by which the paint mist which arises during a change of color and/or during the initial pressurized infeed to an atomizer can be freed at least partially from paint particles.